Geometry
Category : 3rd Class
LEARNING OBJECTIVES
This lesson will help you to:—
Amazing Facts
QUICK CONCEPT REVIEW
Yesterday it was Anu's Birthday. She hosted had a wonderful party. She got number of presents from her family and friends, packed in beautiful boxes of various shapes.
The presents included delicious chocolates which were beautifully packed in round box. Her aunt gifted her doll house which was wrapped in rectangular box. She got a teddy bear from her uncle packed in a large square box.
The birthday cake was a chocolate cake in star shape. All the friends in the party wore cone shaped birthday caps and looked cute.
Anu's mother served delicious round shaped burger, spiral shaped past a (fusili) and cylindrical shaped spring rolls to her friends. There were also potato chips and crescent shaped croissants. Finally sweet spheres or 'rasgullas' were served.
We played many paper games. Anu's mother distributed square shaped construction sheets to everyone and asked them to fold the sheet according to given instructions. She told them that a square sheet had four corners and four sides. She asked them to fold the paper in such a way that it should get five corners, six corners, seven corners and eight corners consecutively. The one who is going to finish first would win a prize. They played the same game with triangular paper too.
Later Anu's mother-asked one minute quiz from kids. It was about the number of faces, number of edges and number of corners in given shapes. Sia was asked that "How many edges are there in a pencil box?. Sia answered. "The edge is where two faces meet and pencil box has twelve edges'. The question to Rina was "How many faces are there in a book?'. Rina replied 'The surface of the solid shape is called its face, hence book has two faces. The quiz master asked Anu 'Which shape has no edges or corners?', to which Anu replied "Sphere has no edges or corners'.
A piece of Tangram was distributed among Anu's friends and they all made different shapes out of those pieces. Everyone enjoyed the games and the party.
Let’s take a look,
At a few cool shapes.
Some look like boxes,
And others like grapes.
A circle is a shape
That is perfectly round
and a sphere is like a ball
bouncing off the ground.
When it has four equal sides
We call it a square
While a cube looks like a box,
Used for gifts that we share.
A triangle has equal sides,
But only just three,
Looks like one side of a pyramid,
I surely agree.
There are plenty of more
Shapes
That you may go and explore
A rectangle looks like,
A fallen old door.
POINT
A point is a small dot in space.
Here sides AB and CB are meeting at a point B. This B point is called a vertex.
RAY
E.g. A ray AB with end-point A is denoted as \[\overset{\xrightarrow{{}}}{\mathop{\text{AB}}}\,\].
LINE SEGMENT
Ex. A line segment AB is written as AB.
A and B are its end-points.
Ex. Line segment of 5 cm.
LINE
Ex. A line AB is written as \[\overset{\overset{{}}{\longleftrightarrow}}{\mathop{\text{AB}}}\,\]
PARALLEL LINES
(i) AB || CD
(ii) Length of x = Length of y.
INTERSECTING LINES
Point |
Line |
Line segment |
Rays |
Denoted by (.) |
Denoted by \[(\overset{{}}{\longleftrightarrow})\] |
denoted by |
Denoted by |
It is a single point in space with no starting or end-point. |
No end- point. |
2 end-point |
1 end-point |
No dimensions |
Indefinite length |
Definite length |
Indefinite length |
Represented using a capital letter ex. O, A, B, |
Represented using a small letter ex: l, m |
Represented using two capital letters denoting the end-points as A, B or P, Q etc |
The end-point is denoted by a capital letter |
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